Year Observations     Objects
1950            2          1 
1951            6          3 
1953            4          2 
1954            2          1 
1955            4          2 
1956            2          1 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978            8          3 
1981            4          2 
1982           12          6 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990           32         14 
1991          444        170 
1992          721        293 
1993         1280        477 
1994         1631        600 
1995         2897       1013 
1996         2895       1024 
1997         1784        618 
1998        21448       9126 
1999        12863       4957 
2000        37960      15676 
2001        39112      15166 
2002        35428      15298 
2003        57952      24008 
2004        45247      17387 
2005        79807      24592 
2006       102757      33049 
2007       187237      58065 
2008       105948      30455 
2009        88867      25107 
2010       141153      37966 
2011       149985      41659 
2012       140862      39087 
2013       214287      61108 
2014       544661     138624 
2015       796044     209507 
2016       644378     167257 
2017       542789     146970 
2018       337125      94789 
2019       848707     207248 
2020       589897     149615 
2021       800533     189330 
2022       606624     173655 
2023       546539     156402 
2024       604425     173666 
2025       534089     152122